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. 2017 Jul 26;3(7):e1700518. doi: 10.1126/sciadv.1700518

Fig. 2. Photoinduced CD signal of the WSe2/MoS2 heterostructure at 10 K.

Fig. 2

(A) Schematic of valley-polarized hole generation in the WSe2 layer within the heterostructure. Upon photoexcitation with LCP light, excitons are resonantly created in the K valley of the WSe2 layer (encircled with a dashed box). Ultrafast charge transfer process then efficiently transfers electrons to the MoS2 layer and leaves resident holes at the K valley in the WSe2 layer. (B) Top: Photoinduced CD spectrum at 3 ns. Bottom: RC spectrum of the WSe2/MoS2 heterostructure. RC spectrum is dominated by the optical absorption near the WSe2 A-exciton resonance at 1.72 eV. The CD spectrum, −Δ(RCσ+ − RCσ−), shows prominent resonant feature near the WSe2 A-exciton peak under LCP pump light at 1.78 eV (black arrow in the RC spectrum). (C) Decay dynamics of the resonant CD signal at 10 K. No decay is observed within 3.5 ns (inset). The decay curve over a longer time scale shows a significant slow decay component with a lifetime of more than 1 μs.